Prevent the removal of a manual 'orderby' attribute in the gallery shortcode.

props nofearinc.
fixes #24868.

Built from https://develop.svn.wordpress.org/trunk@25720


git-svn-id: http://core.svn.wordpress.org/trunk@25633 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Inline documentation for hooks in wp-settings.php.

Props miyauchi.
Fixes #25469

Built from https://develop.svn.wordpress.org/trunk@25721


git-svn-id: http://core.svn.wordpress.org/trunk@25634 1a063a9b-81f0-0310-95a4-ce76da25c4cd